The synthesis of several known metabolites of the prostaglandins is proposed. These compounds would be made available in gram quantities for investigators to assess their physiological responses, particularly in respiratory, circulatory and cardiovascular systems. Readily available supplies of these well-characterized compounds also would be an invaluable aid to biological investigators for accurate identification and quantitation of metabolites in their experimental systems. Preparation of isotopically labeled metabolites would facilitate the development of mass spectrometric and radio-immune assays.